From b5118330ab3e8d5eaaeca4087f2e2e92380678dd Mon Sep 17 00:00:00 2001
From: NeilBrown <neil@brown.name>
Date: Sun, 12 May 2019 15:03:27 +1000
Subject: [PATCH] oceani: allow list of declarations as top level structure

We can have constants, types, etc at top level, as well
a program

Signed-off-by: NeilBrown <neil@brown.name>
---
 csrc/oceani-tests.mdc |  1 +
 csrc/oceani.mdc       | 75 +++++++++++++++++++++++++++++++++----------
 2 files changed, 59 insertions(+), 17 deletions(-)

diff --git a/csrc/oceani-tests.mdc b/csrc/oceani-tests.mdc
index 9850f25..a41b199 100644
--- a/csrc/oceani-tests.mdc
+++ b/csrc/oceani-tests.mdc
@@ -487,6 +487,7 @@ separate file first, then run from there.
 
 ###### output: syn1
 	.tmp.code:3:11: error: unhandled parse error: then
+	oceani: no program found.
 
 ###### test: tokerr
 	program:
diff --git a/csrc/oceani.mdc b/csrc/oceani.mdc
index de899a2..48ce058 100644
--- a/csrc/oceani.mdc
+++ b/csrc/oceani.mdc
@@ -114,6 +114,7 @@ structures can be used.
 		struct token_config config;
 		char *file_name;
 		int parse_error;
+		struct exec *prog;
 		## parse context
 	};
 
@@ -179,7 +180,6 @@ structures can be used.
 			},
 		};
 		int doprint=0, dotrace=0, doexec=1, brackets=0;
-		struct exec **prog;
 		int opt;
 		while ((opt = getopt_long(argc, argv, options, long_options, NULL))
 		       != -1) {
@@ -223,32 +223,31 @@ structures can be used.
 					break;
 			}
 			if (ss)
-				prog = parse_oceani(ss->code, &context.config,
-				                    dotrace ? stderr : NULL);
+				parse_oceani(ss->code, &context.config,
+				             dotrace ? stderr : NULL);
 			else {
 				fprintf(stderr, "oceani: cannot find section %s\n",
 				        section);
 				exit(1);
 			}
 		} else
-			prog = parse_oceani(s->code, &context.config,
-		                    dotrace ? stderr : NULL);
-		if (!prog) {
-			fprintf(stderr, "oceani: fatal parser error.\n");
+			parse_oceani(s->code, &context.config,
+		                     dotrace ? stderr : NULL);
+		if (!context.prog) {
+			fprintf(stderr, "oceani: no program found.\n");
 			context.parse_error = 1;
 		}
-		if (prog && doprint)
-			print_exec(*prog, 0, brackets);
-		if (prog && doexec && !context.parse_error) {
-			if (!analyse_prog(*prog, &context)) {
+		if (context.prog && doprint)
+			print_exec(context.prog, 0, brackets);
+		if (context.prog && doexec && !context.parse_error) {
+			if (!analyse_prog(context.prog, &context)) {
 				fprintf(stderr, "oceani: type error in program - not running.\n");
 				exit(1);
 			}
-			interp_prog(*prog, argv+optind+1);
+			interp_prog(context.prog, argv+optind+1);
 		}
-		if (prog) {
-			free_exec(*prog);
-			free(prog);
+		if (context.prog) {
+			free_exec(context.prog);
 		}
 		while (s) {
 			struct section *t = s->next;
@@ -3544,12 +3543,44 @@ defined.
 		break;
 	}
 
+### Top level structure
+
+All the language elements so far can be used in various places.  Now
+it is time to clarify what those places are.
+
+At the top level of a file there will be a number of declarations.
+Many of the things that can be declared haven't been described yet,
+such as functions, procedures, imports, named types, and probably
+more.
+For now there are two sorts of things that can appear at the top
+level.  They are predefined constants and the main program.  While the
+syntax will allow the main program to appear multiple times, that will
+trigger an error if it is actually attempted.
+
+The various declarations do not return anything.  They store the
+various declarations in the parse context.
+
+###### Parser: grammar
+
+	$void
+	Ocean -> DeclarationList
+
+	DeclarationList -> Declaration
+		| DeclarationList Declaration
+
+	Declaration -> DeclareConstant
+		| DeclareProgram
+		| NEWLINE
+
+	## top level grammar
+
 ### Finally the whole program.
 
 Somewhat reminiscent of Pascal a (current) Ocean program starts with
 the keyword "program" and a list of variable names which are assigned
 values from command line arguments.  Following this is a `block` which
-is the code to execute.
+is the code to execute.  Unlike Pascal, constants and other
+declarations come *before* the program.
 
 As this is the top level, several things are handled a bit
 differently.
@@ -3560,7 +3591,17 @@ analysis is a bit more interesting at this level.
 ###### Binode types
 	Program,
 
-###### Parser: grammar
+###### top level grammar
+
+	DeclareProgram -> Program ${ {
+		struct parse_context *c = config2context(config);
+		if (c->prog)
+			type_err(c, "Program defined a second time",
+			         $1, NULL, 0, NULL);
+		else
+			c->prog = $<1;
+	} }$
+
 
 	$*binode
 	Program -> program OpenScope Varlist Block OptNL ${
-- 
2.43.0